docs: def do_login():
      """ Attempt to auth using single login. Rate limited at the site level. """
  
      dt_filter = lambda x: x >= datetime.utcnow() - timedelta(seconds=60)
      app.config['AUTH_ATTEMPTS'] = filter(dt_filter, app.config['AUTH_ATTEMPTS'])
  
      if len(app.config['AUTH_ATTEMPTS']) > app.config['AUTH_RATE_LIMIT']:
          return redirect(url_for('login',
                                  alert="Rate limit exceeded. Try again in 60 seconds."))
  
      if request.form.get('password') == app.config['APP_PASSWORD']:
          login_user(SingleAuthUser)
          return redirect('/')
  
      app.config['AUTH_ATTEMPTS'].append(datetime.utcnow())
      return redirect(url_for('login', alert="Incorrect password."))